@satyakam: What 'moneymoney' has mentioned here is perfectly right. There is no trick except to concentrate on the picture you are seeing and try to read the letters and type them.
I think that they may be using some timer (which one site was using) for each picture. You have to type the letters within certain limit then only the same would be credited to your account. I am not sure about this but as many members are saying that their balance is not increasing I am just talking about the possibility for not getting the credits.
@moustafa: this site is paying honestly at least that is sure.... no hidden rules, no conditions attached, no temptation as there is no referral system and payment just within seconds....! although the earning may be slower it is certain.
Today 10 cents more are credited to my account from this site.